Compressor unloading mechanism



June 21, 1932. H. B. HALVORSEN COMPRESSOR UNLOADING MECHANISM Filed Oct.29, 1928 fizz/with Ha? ZePYB. HlZum'Jen/ fig Auk ,4- mm,

Patented June 21, 1932 NETED STATES PATENT OFFICE HALBERT B. HALVORSEN,OF MICHIGAN CITY, INDIANA, ASSIGNOR TO SULLIVAN MACHINERY COMPANY, ACORPORATION OF MASSACHUSETTS COMPRESSOR UNLOADING MECHANISM Applicationfiled October 29, 1928. SerialNo. 315,734.

The invention relates to compressor unloading mechanism and particularlyto high pressure cylinder relief valve mechanisms for compoundcompressors. It is an object of the invention to provide an improved andsimplified compressor unloading system. Another object is to provideimproved high pressure cylinder relief valve controlling mechanism.Still another object is to provide an improved high pressure cylinderunloading mechanism, automatically controlled by fluid pressure in theintercooler. A more specific object is to provide an improved highpressure relief valve mechanism of extremely compact construction tofacilitate manufacture and installation. Other objects and advantages ofthe invention will hereinafter more fully appear.

For purposes of illustration 1 have shown in the accompanying drawingone-embodiment which my invention may assume in practice.

In the drawing Fig. 1 is a diagrammatic view in side ele vation of anangle compound compressor having my invention associated therewith.

Fig. 2 is a fragmentary view of the high pressure cylinder at rightangles to Fig. 1, showing part of the mechanism of my invention.

' Fig. 3 is a central vertical section on line 33 of Fig. 2 through anillustrative form of my improved high pressure cylinder unloadingmechanism which is automatically controlled by fluid pressure in theintercooler. i

Fig. 4 is a central transverse section through this unloading mechanismon line 44 of Fig. 3. I

In the illustrative embodiment as shown in Fig. 1, the angle compoundcompressor is generally indicated at 1 and has a horizontal low pressurecylinder 2 and a vertically arranged high pressure cylinder 3. Anintercooler 4t is connected with the low pressure cylinder by pipe 5 andwith the high pressure cylinder by another pipe 6. The high pressurecylinder is shown discharging compressed fiuid into a receiver tank 7through a discharge pipe 8. Any usual form of pilot valve controlledunloading mechanism may be employed for unloading the low pressurecylinder; Since the particular form of'the unloading mechanism for thelow pressure cylinder forms no part of the present invention, it has notbeen described or shown in detail. Oneform which this unloader mayassume is indicated at 9 which is a total clo sure inlet valve forcontrolling the intake of fluid through the opening 10, control be.- ingeffected by a pilot valve P. V.

Novel means for unloading the high pressure cylinder a definite timeafter unloading of the low pressure cylinder will now be described. Itwill be readily understood that it is very desirable to allow the highpressure cylinder to operate effectively for a few strokes after the lowpressure cylinder has been rendered ineffective, in order that the airremaining in the interco-oler under an intermediate pressure, may bepumped out. The necessity of relieving the high pressure cylinder whenthe compressor runs unloaded for any considerable length of time isreadily understood by those skilled in the art. If this were not done,the high pressure cylinder would take in fluid from the intercooler at afairly high vacuum and compress it up to thedischarge pressure. Theveryhigh ratioof compression which would take place would cause excessiveheating and=possibly explosions. The novel mechanism illustrated hereincomprises valve mechanism generally indicated by the member 11 havingseparate connections 12 and 13 with opposite ends of the high pressurecylinder. The interior of the valve housing has chambers 14 and 15 whichare connected by passages 17 and 18 respectievly with a common vent ordischarge pipe 16 which opens to the atmosphere.

Communication between the opposite ends of the high pressure cylinderand the atmosphere is controlled by meansof annular plate valve 19 and20 which control series of ports 21 and 22 which connect the chamhere 14and 15 with the respective connections 12 and 13. The plate valves closeupon flat seats formed on the hardened plate memhers 23 and 24 and whichsurround theseries of ports .21 and 22 respectively. When these valvesare free to move, the high pressure cylinder is rendered ineifectivesince the valve plates 19 and 20 may now act as outwardly opening checkvalves. In other words, the building up of a slight degree of pressurein either end of the high pressure cylinder will open the valve 19 or 20to vent the end to atmosphere through chamber 14 or 15; but sucking ofair back into the cylinder from the chambers 14 and 15 is prevented bythe valves 19 and 20.

For the purpose of controlling these valves and holding them againsttheir seats on the plates 23 and 24 during the time that the compressoris operating loaded, I have provided a novel fluid pressure operatedmechanism which will now be described. 7 Since the construction is thesame at both the upper and lower ends, only one end will be considered.Arranged on the opposite side of the valve 19 from its seat on the plate23, I have provided a yoke 25, which is provided with an annular surface26, adapted to' bear against the valve 19. The yoke 25 is guided in itsmovement by upwardly extending guides 27 cooperating with a recess 28 inthe plate 23. The yoke at the other end, is attached by any suitableretaining means such as the bolt 29 to a flexible diaphragm 30. Thediaphragm for the lower end is indicated at 31 and these two diaphragrnscooperate with an annular casing 35 to form a closed chamber which isconnected by pipe 32 with the intercooler. The connection to theintercooler may be made at any convenient location. The diaphragms and31 are clamped in position between the casing 35 and the respectivevalve housings. The passages 17 and 18 may, as shown in this preferredembodiment, be extended through the diaphragms, and continued so as tomeet within the annular casing 35. The discharge pipe 16 is threadedinto tne casing 35 and I communicates with the juncture of the pas-,sages 17 and 18. For the purpose of limiting the inward movement of thediaphragms and yokes, there is provided a central abutment 33, againstwhich the bolt heads, holding the diaphragms in position, are adapted tostrike. The difierent sections of the valve housing, the annular casing35, the diaphragms 30 and 31, and the plates 23 and 24 are all held inassembled relation by means of longitudinally extending side bolts 34,which are shown in section in Fig. 4.

The operation of my improved relief valve controlling mechanism will nowbe described. Assume that the compressor is operating normally and itbuilds up a pressure in the receiver tank which will trip the pilotvalve of the low pressure cylinder unloader. The unloader valve 9 isthen closed and the low pressure cylinder rendered ineffective. 0on4tinued operation of the compressor will cause a rapid reduction 1npressure in the lntercooler, and after a few strokes this pressure willbe reduced to about 4 or 5 lbs. per square inch above atmosphere. Thispressure is of course, communicated to the diaphragms 30 and 31 and theholding pressure on the valves 19 and 20 is reduced to such an extentthat the pressure within the high pressure cylinder, tending to openvalves 19 and 20 will push back the yokes 25, 25 alternately, therebyventing the ends of the high pressure cylinder directly to atmospherethrough chambers 14 and 15, passages 17 and 18, and the pipe 16. Thiswill cause a still further reduction of pressure in the intercooler;and, as soon as the intercooler pressure is below atmospheric pressure,the yokes 25 are forced back by the atmospheric pressure in chambers 14and 15, causing the bolts 29 to press against the abutment 33. Thevalves 19 and 20 are now permitted to operate freely as check valves andthus relieve both ends of the high pressure cylinder. When pressure inthe receiver tank is reduced to the point required to cause the openingof the unloader 9, the low pressure cylinder will become eifective andcause a rapid building up of pressure in the intercooler. This pressuredoes not need to be materially greater than atmospheric pressure tocause the closing of valves 19 and 20 against the pressure in the highpressure cylinder, since the effective pressure area on each of thediaphragms is much greater than the opposed pressure area on one of thevalves. Probably 5 or 6 lbs. would be sufficient with a practical designof the device. The valves 19 and 20 will thus be held closed by thediaphragms 30 and 31; and the intercooler pressure will build up tonormal, and supply the high pressure cylinder. The operation of the highpressure cylinder unloading mechanism is thus made automatic anddependent upon the operation of the low pressure cylinder unloader,although it is not connected thereto.

As a result of my invention, it will be apparent that a very compact andsimplified means has beendevised for effectively relieving the highpressure cylinder at just about the proper time. The device is verycompact since it only comprises a single valve unit which may be easilyinstalled.

While I have in this application specifically described one form whichthe invention may assume in practice, it will be understood that thisform of the same is shown for purposes of illustration and that theinvention may be modified and embodied in various other forms withoutdeparting from its spirit or the scope of the appended claims.

What I claim as new and desire to secure by Letters Patent is:

1. In a relief valve type unloading means for the high pressure cylinderof a compressor which comprises a low pressure cylinder, a high pressurecylinder, and an intercooler, in combination, an annular flat valveseat, an

annular plate valve mounted for limited movement relative to said seat,vand1fluid pressure operated mechanism controlled by fluid pressure inthe compressor intercooler for controlling said platevalve,said.mechanism including a reciprocable member movable relative tosaid annular plate valve, said reciprocable member engaging said platevalve to hold the same seated during normal operation of the compressorand releasing said plate valve during unloading of the high pressurecylinder, and said plate valve controlling a vent from the high pressurecylinder.

2. In a relief type unloading means for the high pressure cylinder of acompressor which has a low pressure cylinder, a high pressure cylinderand an intercooler, in combination, relief valves one connected to eachend of the high pressure cylinder to relieve pressure fluid pumped bythe same, and means for v holding said valves closed during normalconditions in the intercooler, including a pair of movable members onecooperating with each relief valve, said movable members having each asurface subjected to intercooler pressure, said surfaces constitutingwalls of a common pressure chamber connected to said intercooler.

3. In an unloading mechanism for the high pressure cylinder of acompressor which has a low pressure cylinder, a high pressure cylinder,and an intercooler, in combination, relief valves one connected to eachend of the high pressure cylinder to relieve pressure fluid pumped bythe same, and means for holding said valves closed during normalpressure conditions in the intercooler, including a casing connected tothe intercooler, said casing having Walls constituted by diaphragms onecooperating with each relief valve.

4. In an unloading mechanism for the high pressure cylinder of acompressor which has a low pressure cylinder, a high pressure cylinder,and an intercooler, in combination, relief valves one connected to eachend of the high pressure cylinder to relieve fluid pressure pumped bythe same, a pair, of yokes one cooperating with each relief valve forholding the same closed during normal pres sure conditions in theintercooler, a pair of diaphragms one connected to each yoke foractuating the same, and a casing defining a chamber formed withopenings, two of said openings being closed by said diaphragms and athird being connected to the inter cooler.

5. A relief valve mechanism adapted to unload both ends of the highpressure cylinder of a compressor having a low pressure cylinder, a hi hpressure cylinder and an intercooler, comprising a casing, said casingproviding a chamber with a plurality of openings, a pair of members eachhaving a surface constituting a movable-wall closing one of saidopenings, means adapted to connect a third of said openings with theintercooler, and a pair of relief valve mechanisms, one controlled byeach of said members.

6. In a relief valve mechanism for unloadingboth ends of the highpressure cylinder of a compressor which has a low pressure cylinder, ahigh pressure cylinder, and an intercooler, in combination, a valvecasing having its opposite ends connected one to each end of the highpressure cylinder, a valve and valve seat in each end of said casing, apair of diaphragmsmountedin said casing between said valves for holdingthe latter in closed position when said diaphragms are subjected topressure, and means for subjecting said diaphragms to pressure in theintercooler.

7 L In an unloading system for a compressor having a low pressurecylinder, a high pressure cylinder, and an intercooler, a unitary reliefvalve mechanism for unloading both ends of the high pressure cylinder,comprising a valve casing having a centralchamber connected to theintercooler, diaphragms at opposite sides of said chamber subjected tointercooler pressure, a ported valve seat mounted in each end of saidcasing,.said seat-s communicating one with each end of the high pressurecylinder, annular plate valves one mounted for limited movement relativeto each seat, and yokes one connected to each of said diaphragms andarranged tobear against one of said valves.

8. In a compressor unloading system, the combination as defined in claim7 wherein each of said yokes is provided with means for guiding itsrespective annular plate valve. 9; Relief valve mechanism for unloadinga high pressure cylinder of a compressor having alow pressure cylinder,a high pressure cylinder, and an intercooler, comprising meansprovidinga passage connecting an. end of the high pressure cylinder toatmosphere, avalve mechanism for controlling said passage-comprising a.valve seat, a guard and a valve loosely disposed between. said guard andseat when the cylinder is unloaded, and meansresponsive to intercoolerpressure for reciprocating said guard for holding said valve seatedwhenthe pressure in the intercooler is above a predetermined point and forreleasingsaid valve when intercooler pressure drops below apredetermined point 10. A relief valve mechanism for unloadi-ng bothends of the high'pressure cylinder of a compressor having a low pressurecylinder, a high pressure cylinder, and an intercooler, comprising acasing having two movable walls, a pair of relief valves controllingpassages connecting the opposite ends of the high pressure cylinder toatmosphere, and means connecting each of said movable walls to a reliefvalve for controlling unloading ion izo

of the high pressure cylinder, said casing being connected to theintercooler whereby said relief valves are held closed when theintercooler pressure exceeds a predetermined amount and are released tovent fluid pressure pumped by the high pressure cylinder whenintercooler pressure falls below a predetermined amount.

11. Relief valve mechanism for venting both ends of a high pressurecylinder of a compressor having a low pressure cylinder, a high pressurecylinder, and an intercooler, comprising opposed valve seats, valvescooperating with said seats and oppositely moving on opening, andactuating means for holding said valves seated during normal pressureconditions in the intercooler, said actuating means comprising a casinghaving two movable walls, one connected to each relief valve, saidcasing being connected to the intercooler.

12. In an unloading means for a doubleacting pump cylinder, meansforming a pair ofpassages adapted to communicate with the ends of acylinder, a pair of valves controlling communication of said passageswith the at-' mosphere, and means for normally holding said valvesclosed including means forming a pressure chamber having oppositelymovable walls and means through which said walls Ina-y respectively movesaid valves to closed position.

13. In an unloading means for a pump cylinder, means forming a passageadapted to communicate with an end of the pump cylinder, and mechanismfor controlling communication of said passage with the atmosphereincluding a valve seat, a coaxial valve guard and guiding member, avalve member cooperating with said seat and guided and limited in itsmovement relative to the seat by said guard and guiding member, andmeans for moving said guard and guiding member relative to said seat toclamp the valve'on the seat. I

14:. In an unloading means for a pump cyl inder, means forming a passageadapted to communicate with an end of the pump cylinder, and mechanismfor controlling communication of said passage with the atmosphereincluding a valve seat, a coaxial valve guard and guiding member, avalve member cooperating with said seat and guided and limited in itsmovement relative to the seat by said guard and guiding member, and pressure fluid operated means for moving said guard and guiding memberrelative to said seat to clamp the valve on the seat.

15'. In an unloadingmeans for a double acting pump cylinder, incombination, means forming a pair of passages adapted to communicatewith the ends of a cylinder, a pair of valves controlling communicationof said passages with the atmosphere, and means

